Combustion chamber for gas turbines

ABSTRACT

An axial flow combustion chamber for gas turbines and the like comprising an outer shell surrounding an open-ended flame tube and defining an annular jacket, a portion of the air introduced through a forward end of the combustion chamber flowing into an up-stream combustion zone in the flame tube to sustain the combustion of the fuel charge, the other portion being diverted into the annular jacket and introduced into the flame tube at a predetermined distance downstream from the combustion zone to cool and dilute the combustion gases prior to their discharge at the other end of the flame tube.

I United States Patent 11 1 1111 3,874,169

Andersson et al. 5] Apr. 1, 1975 [5 COMBUSTION CHAMBER FOR GAS 2.742.762 4/1956 Kuhring 60/39.65 TURBINES 2.930.194 3/1960 Perkins 4 60/39.65 3 O99l34 7/1963 Calder ct al. r t 60/39115 X Inventors: Lelf Anderssen; Laszlo y u 3.280.555 10/1966 Charpentier ct al. 60/3923 both Swede FOREIGN PATENTS OR APPLICATIONS 1 Assigns/=1 stal-Laval Turbi" Finsptme 512723 1/1921 France 60/3965 Sweden [22} Filed: Sept. 27, 1973 Primary Etamincr-Carlton R. Croyle Assistant Etaminer-Robert E. Garrett [21] APPI- N05 4011440 Attorney, Agent. or Firm-Eric Y. Munson Related U.S. Application Data [63] Continuation of Scr. No. l97,345. Nov. l0, 1971. [57] ABSTRACT abandoned. An axial flow combustion chamber for gas turbines and the like comprising an outer shell surrounding an Foreign Application Priority Data open-ended flame tube and defining an annular jacket. Jan. 14, 1971 Sweden 383/7 a portion of the air introduced through a forward end of the combustion chamber flowing into an up-stream 521 U.S. c1. 60/39.65, 431/352 eembustien Zone in the flame tube to Sustain the 51 Int. Cl. F02C 7/00 bustitm 9f the fuel charge. the ether Pttrtitm being 5 Field f Search H 0 39 5 3923 395 verted into the annular jacket and introduced into the 43 453; 239/41 5 430 431; 2 1/113 flame tube at a predetermined distance downstream from the combustion zone to cool and dilute the com- 5 References Ci bustion gases prior to their discharge at the other end UNITED STATES PATENTS flame tube- 2,601,390 6/1952 Hague 6. /3965 2 Claims, 3 Drawing Figures COMBUSTION CHAMBER FORGAS TURBINES BACKGROUND OF THE INVENTION The present invention relates to a combustionchamber for a gas turbine and is a continuation of copending application Ser. No. l97.345. now abandoned, filed Nov. 10, l97l.

Such a combustion chamber comprises the combustion chamber proper or flame tube and a shell surrounding the flame tube into which combustion chamber air for sustaining the combustion process and for diluting the hot combustion gases is blown. The diluting air is blown in through holes in the surface of the flame tube at a certain predetermined distance downstream from the ignition zone.

Heretofore, it has been considered most expeditious to drill the holes for admitting the dilution air. straight in radial direction towards the centrum of the flame tube. However. according to the invention it is proposed instead to arrange some of the holes obliquely in relation to the central axis of the flamp tube so that the combustion gases and diluting air are more thoroughly mixed and thus a more even temperature distribution is obtained.

In accordance with the invention the aggregate crossscctions of the holes in various directions is adjusted in relation to each other partly by the choice of the number of holes in the various groups and partly by providing the holes with replaceable sleeves having different diameters so that a suitable distribution of hole crosssections can be achieved in the various directions.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described with reference to the accompanying drawings in which FIG. I shows how the combustion chamber according to the invention is arranged in a gas turbine; FIG. 2 shows a cross-section through the flame tube and the distribution and direction of the holes in the wall of the tube. FIG. 3 shows a section through a hole according to a more detailed view of the invention.

SUMMARY OF THE INVENTION FIG. 1 shows purely schematically a gas turbine plant comprising an axial compressor 1, a combustion chamber 2 according to the invention, a turbine 3 for driving the compressor 1 and a power turbine 4 which drives an electric generator 5.

The combustion chamber 2 comprises an outer shell 6 surrounding a flame tube 7 defining an annular chamber orjacket 7a terminating in a nozzle 7h. Compressed air from the compressor 1 is blown into the lefthand or upstream end of the combustion chamber 2 and a portion of the air flows into the ignition zone 8 of the flame tube where fuel introduced from a source not shown is ignited. In order to dilute the hot combustion gases and to cool them before they are supplied to the turbines 3 and 4, the other portion of the pressurized air which is diverted into the jacket 7a is introduced into the flame tube through holes 9. This air portion does not take part in or sustain the combustion process but in order to produce the desired effect it must be thoroughly mixed with the combustion gases.

For this purpose, the holes or apertures are arranged according to the invention as seen in FIG. 2, which shows a section I-l through the flame tube 7, the lines with arrows indicating the flow pattern of diluting air from the apertures). It will be noted that some of the apertures 9a are directed radially towards the central axis of the flame tube, whereas other apertures 9/2 are directed obliquely in relation to the center line of the tube 7. The apertures 9lr are preferably arranged in pairs so that the corresponding two air streams will be symmetrical in relation to the: center line of the tube. This pattern of air currents produces more thorough mixing ofthe combustion gases and the diluting air. and thus a more uniform temperature distribution across the entire cross-section of the flame tube. If all the apertures and consequently all the air streams had been directed radially. the mixture would only be effective towards the centrum of the flame tube and the temperature near the wall of the flame tube would be considerably higher than at its centrum.

The number of apertures in different directions should be more or less the same in order to achieve uniform air distribution around the entire circumference of the tube. This air distribution can be further modified by varying the cross-section of the various aperturcs 9. This can be done as seen in FIG. 3 which shows one'of the holes 9/; in the same section as in FIG. 2.

In the modification shown in FIG. 3, the aperture has been formed by means of a fixed sleeve 10 which is welded into the wall of the flame tube 7. Inside the sleeve 10 is a replaceable sleeve 11 and by using sleeves 11 having different diameters in the radially and obliquely directed apertures, the desired crossscctional distribution with consequent improved air distribution can be achieved. Behind the permanent sleeve 10 in FIG. 3. a second sleeve 12 is provided which is symmetrical with the sleeve 10 in relation to the corresponding radius in the flame tube.

We claim:

1. An axial flow combustion chamber for gas turbines and the like comprising:

a. a longitudinal flame tube having a circumferential wall, an air inlet opening at one end and a discharge opening at the other end;

b. a shell surrounding said flame tube at a spaced distance from said circumferential wall to define an annular jacket having an air inlet opening and joined at one end to said circumferential wall adjacent the discharge opening thereof;

c. means for introducing air into the combustion chamber;

d. means for admitting a portion of said air into an upstream fuel combustion zone in said flame tube;

e. means for conducting another portion of said air into said jacket;

f. a plurality of apertures spaced circumferentially in the wall of said flame tube;

g. said apertures being located downstream from said fuel combustion zone for introducing air from said jacket into said flame tube to cool and dilute the combustion gases prior to their discharge through said discharge opening;

h. a first group of said apertures being effective to direct streams of air in a direction radially towards the center line of the flame tube, and being spaced alternately between s second group of apertures. said second group of apertures comprising first and second apertures disposed at an essentially common circumferential location, and directed to effect a pair of oppositely circumferentially diverging streams with respect to a radius of the flame tube passing through said common circumferential location to intercept said radial streams at a spaced distance from the center line of the flame tube.

. said pair of diverging streams having a relatively equal angle of divergence to produce a symmetrical flow pattern jointly with said radial streams at 

1. An axial flow combustion chamber for gas turbines and the like comprising: a. a longitudinal flame tube having a circumferential wall, an air inlet opening at one end and a discharge opening at the other end; b. a shell surrounding said flame tube at a spaced distance from said circumferential wall to define an annular jacket having an air inlet opening and joined at one end to said circumferential wall adjacent the discharge opening thereof; c. means for introducing air into the combustion chamber; d. means for admitting a portion of said air into an upstream fuel combustion zone in said flame tube; e. means for conducting another portion of said air into said jacket; f. a plurality of apertures spaced circumferentially in the wall of said flame tube; g. said apertures being located downstream from said fuel combustion zone for introducing air from said jacket into said flame tube to cool and dilute the combustion gases prior to their discharge through said discharge opening; h. a first group of said apertures being effective to direct streams of air in a direction radially towards the center line of the flame tube, and being spaced alternately between s second group of apertures, said second group of apertures comprising first and second apertures disposed at an essentially common circumferential location, and directed to effect a pair of oppositely circumferentially diverging streams with respect to a radius of the flame tube passing through said common circumferential location to intercept said radial streams at a spaced distance from the center line of the flamE tube. i. said pair of diverging streams having a relatively equal angle of divergence to produce a symmetrical flow pattern jointly with said radial streams at a spaed distance about the flame tube.
 2. A combustion chamber according to claim 1, in which a replaceable sleeve having a wall of predetermined thickness is inserted into the apertures to produce a predetermined air distribution pattern. 